FBI general counsel Valerie Caproni will outline what the bureau is calling the "Going Dark" problem, meaning that police can be thwarted when conducting court-authorized eavesdropping because Internet companies aren't required to build in backdoors in advance, or because technology doesn't permit it.

Any solution, according to a copy of Caproni's prepared comments obtained by CNET News, should include a way for police armed with wiretap orders to conduct surveillance of "Web-based e-mail, social networking sites, and peer-to-peer communications technology."

The last example, which was floated last fall, is likely to be the most contentious. When an encrypted voice application like Phil Zimmermann's Zfone is used, the entire conversation is scrambled from end to end. It's like handing a letter directly to its recipient--bypassing workers at the neighborhood post office, who could be required to forward a copy to the FBI. Forcing companies like Zfone and Skype, which also uses encryption for peer-to-peer calls, to build in backdoors for police access was rejected in the 1990s and would mark a dramatic departure from current practice.